Alphabetical List of Convoy Codes.
From "The Allied Convoy System 1939-1945" by Arnold Hague ©.
Published in 2000 by Chatham Publishing. ISBN 1-55125-033-0.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

O.

Code
Notes
OAThames to Liverpool, with an Adantic element 1939 to July 1940. After July 1940, Methil to Liverpool northwards, to disperse in North Atlantic, sometimes after juncture with OB of same number.
OBLiverpool outward, usually joined by the OA of same number.
OCMelbourne to Newcastle, NSW
OGOutward to Gibraltar from UK.
OMOran to Marseilles, 1944 series.
ONOutward to Norway, Methil to Bergen, in 1939-40.
ONOutward North. Liverpool etc to North America 1941 onwards.
ON(F)Alternate convoys of the ON sequence (see above).
ON(S)Alternate convoys of the ON sequence (see above).
ONSOutward North Slow, Liverpool etc to North America 1943 onwards.
OSOutward Southbound, Liverpool etc to Freetown 1941 onwards.
OSSSouthward extension of OS from Freetown.
OTOutward Trinidad. Two series, one local Caribbean, one to North Africa.
OWOutward Westward, Australia/India, numbers reused.

Note:
O.G., O.N., also indicate Liverpool sections before R/V with other sections.
(R), (M), (O) and (U) after 'O' convoys indicate Clyde, Milford Haven, Oban and Loch Ewe sections.
O.S. also indicates Liverpool sections before R/V with other sections.

Converted from the original by kind permission of Mrs. Gill Hague.